It's a pretty simple pitch: Agree to keep your land undeveloped for conservation purposes and pay nothing in property taxes on it ever again.

The Taxation and Budget Reform Commission, a group appointed by the governor and lawmakers that can place constitutional amendments on the ballot, unanimously approved the measure Wednesday. Voters will consider it on November's ballot, and it requires at least 60 percent approval to pass.

It comes at a time when counties are struggling with how to oversee rural lands, trying to strike a balance between those who want to preserve the agricultural flavor of the past against those who see the area ripe for development.

This new proposal, which equates to taxpayers helping subsidize conservation land, so far has received mixed reviews from officials on the Treasure Coast, with most wanting to see more details on how the plan would be implemented.

"For us, I think it is a wonderful idea for assisting some large land owners, who would let their lands remain as they are today," said Martin County Commission Chairman Doug Smith. "In counties where they have not gotten a good balance of public and private lands, it might not be so good."

The easements wouldn't necessarily require public access, but placing one on a property would limit the land uses and reduce its market value.

Also, it would reduce tax rolls at a time when governments already are facing diminishing coffers.

Indian River County Commissioner Peter O'Bryan said he wants to know if the proposed tax exemption would require the owner to permanently set aside the land as conservation or if the owner could later switch it back.

"They may just want to ride out a bad real estate market," O'Bryan said.

Those details, and other specifics, such as how large the undeveloped land would have to be to qualify, must still be worked out by lawmakers. Conservation land has been set aside in various ways throughout the Treasure Coast, sometimes in the form of easements, other times by having developers buy credits for setting aside land, such as what occurred with Adams Ranch in St. Lucie County.

In 2007, the Indian River County Commission spent $23.2 million buying conservation easements on agricultural lands in the western parts of the county, plus $12 million more for development rights to Ralph Sexton's Treasure Hammock Ranch west of Vero Beach and $11.2 million for rights at Padgett Branch in the county's southwest corner. The tax breaks would likely apply to owners like Sexton who have already sold development rights, even though those lands typically have agricultural exemptions that reduce taxes.

That worried O'Bryan.

"You would not want to see all the taxes go away," he said.

St. Lucie County Commissioner Doug Coward, who has been fighting Florida Power & Light Co.'s proposal for wind turbines on county and state conservation lands, said he supports conservation easements but is skeptical whether the tax incentives alone are enough to entice landowners to set aside their property. If an owner has only altruistic goals, the program could work; but for those focused on the financial end, tax breaks alone likely won't motivate them.

The measure has received initial support from the Trust for Public Lands, the Nature Conservancy and the Florida Wildlife Federation. It's similar to a proposal advocated in 1998 by the Constitutional Revision Commission that ultimately died.

Indian Riverkeeper Kevin Stinnette said he wants to see more details on the proposal to make sure it's a genuine way to promote conservation, not simply a loophole for speculators in a down real estate market. While Florida has "greenbelt" taxes for those involved in agricultural production, some developers have skirted the intent of it by "renting cows" on those plots of land.

"The devil is in the details," Stinnette said. "Fortunately, we have until November to examine it."

NO TAXES ON UNDEVELOPED LAND?

Ballot language, as approved by the Taxation and Budget Reform Commission for the November ballot:

AD VALOREM TAXATION OF LAND USED FOR CONSERVATION PURPOSES: This amendment to the State Constitution authorizes the Legislature to provide by law for an ad valorem tax exemption for conservation purposes as defined by general law.

The St. Petersburg Times and staff writers Joe Crankshaw and Elliott Jones contributed to this report